RTV Silicone for Garboard Plug

[proslambanomenos]

Hi all,

It appears that most people recommend using 5200 sealant for installing a brass garboard plug flange. I was at a marine store the other day and the salesperson said I could use this stuff and it would work just as well:

http://www.iboats.com/Hi_Temp_RTV_G...0520432--**********.933744161--view_id.132317

Is this true? Would you use it to seal the flange? They had this stuff on discount because it was red and doesn't sell, but i don't really care because the garboard is underwater and out of sight.

Thanks!

 

[thrillhouse700]

Re: RTV Silicone for Garboard Plug

Im a noob and drunk right now buuuuuut, I used that stuff in the shop (cars) and everyone here swears by 5200. Also, sometimes salespeople don't klnow there a-hole from a hole in the ground. So maybe get a second opinion from a marine shop or wait for someone else to reply here. I am going with 5200 on mine.

 

[Lion hunter]

Re: RTV Silicone for Garboard Plug

I wouldn't. Water pressure at the level of the plug is very significant. 5200 is a proven marine sealant that works under that type of pressure and can withstand the marine environment. The RTV may work, but then again it may not. I don't use the fast cure and it's a bit cheaper and always available at the HD. Not worth the savings to risk it.

 

[lowkee]

Re: RTV Silicone for Garboard Plug

I can't say not to use it, as I don't know if it will work or not. Here is my scenario.. 5200 is $10.. that is $6.. a transom replacement (if it doesn't work) is $400. Is $4 really going to break your bank? If it is.. just wait until water begins to trickle in.. Everyone recommends 4200 and 5200 because it works, no questions about it.

Heck, I'm normally pretty happy when I only spend $10 for something boat related.. and my boat hasn't even hit the water yet!

 

[109jb]

Re: RTV Silicone for Garboard Plug

The water pressure isn't what I would call significant (about 1.25 psi at 3 feet below the surface), but I would use 5200 anyway. Silicone basically doesn't really stick to anything. It can many times just be rolled of of whatever surface it was applied to with firm pressure. You ain't gonna do that 5200.

 

[Lion hunter]

Re: RTV Silicone for Garboard Plug

109, you are correct. I had in my mind the pressure on the square footage of the transom, not the 3-4 sqin of the plug surface. Thanks for the correction.

 

[bigredinohio]

Re: RTV Silicone for Garboard Plug

I can't say not to use it, as I don't know if it will work or not. Here is my scenario.. 5200 is $10.. that is $6.. a transom replacement (if it doesn't work) is $400. Is $4 really going to break your bank? If it is.. just wait until water begins to trickle in.. Everyone recommends 4200 and 5200 because it works, no questions about it.

Heck, I'm normally pretty happy when I only spend $10 for something boat related.. and my boat hasn't even hit the water yet!

I was at a boat store and they had 5200 for $23.00 A TUBE!!!

 

[Lion hunter]

Re: RTV Silicone for Garboard Plug

HOLY COW!

The 10oz tube at HD was only $11.00.

 

[Mark42]

Re: RTV Silicone for Garboard Plug

Attwood's polysolfide caulk ( same as 4200) is $8 for a tube about 8" long at Walmart.

And everyone is right. Don't use silicone. I just re-installed my garboard drain and had to scrape off lots of silicone. It came right off with my fingernail. Then the surface was cleaned with a fine sandpaper, then washed with alcohol. Also, take the time to mix up some epoxy and coat the inside of the hole drilled through the transom so water pooling on the inside of the garboard drain (ie the bilge) can not soak into the plywood. I sanded the hole clean, then mixed about a tablespoon full, and using my finger with a latex glove on, smeared the epoxy on the inside. When curing, I mixed up another batch and applied again. Felt like a doctor checking out your prostate.


BTW, when putting the sealer on the garboard drain, fill the entire recess on the back side of the drain, do not just smear it along the edge. Also force some into the screw holes with your finger. The recess is there to hold the sealer. When the screws are tightened, some should squeeze out the edges, just wipe it clean. The sealer held in by the recess will seal, no need for globs on the outside.

 

[fishrdan]

Re: RTV Silicone for Garboard Plug

I was at a boat store and they had 5200 for $23.00 A TUBE!!!

HOLY COW!

The 10oz tube at HD was only $11.00.

Boaters world (when they were open) had it for $16/10oz tube HD had the same thing for $6-7.

BTW, 5200 cures better in a humid environment. I live in the desert and it can take 1-2 weeks for the stuff to dry so it's not tacky. I had a couple of small parts that I 5200'ed, put 1" of water in a 5 gallon bucket and something to keep the parts out of the water, but up in the humid air, capped it off and the parts were dry to the touch in 1 day. If I have to 5200 anything in the future I'm going to cover it with a moist paper towel and plastic bag, being sure not to let the towel touch the 5200. I repaired a crack in the bottom of my 100 qt cooler with 5200, misted it with water to kick the cure and it left water spots in the 5200.

 

[Lion hunter]

Re: RTV Silicone for Garboard Plug

I usualyy mist it and have never had a problem. Had a toilet tank with a crack in it. Spread 5200 on the inside and filled it back up. Cured with no problems at all. It's great stuff. I remember the first time I used it when living in S. AZ. I thought I had bought some terrible stuff. Like you said 1-2 weeks later it was still tacky. Took the boat out (5200 was in the splash well) and it got wet and was cured by the end of the day.

 

[proslambanomenos]

Re: RTV Silicone for Garboard Plug

Thanks everyone, I will use the sealant and not the silicone.

Also, take the time to mix up some epoxy and coat the inside of the hole

When you say "mix up some epoxy" are you referring to a specific brand or formulation? Anything I should be aware of for this? I would like to do this before I install the plug.

 

[legoman67]

Re: RTV Silicone for Garboard Plug

he is refering epoxy resin, or polyester resin, it doesnt really matter..

it just protects the bare wood that is exposed inside the hole, thats where the rot started on our transom, but we dont have a drain plug anymore

 

[Mark42]

Re: RTV Silicone for Garboard Plug

If you don't have epoxy resin or polyester resin, then pick up the double tube applicator of "marine" grade epoxy from the hardware store, or even the regular epoxy . Depot and Lowes usually has an epoxy rated for marine use. Sand the hole clean, probe with a screwdriver to ensure no rot, and smear the epoxy inside the drain hole to seal up any exposed plywood. Typically the transom outer skin is rather thick fiberglass at that point, so only a small section of the ply might be exposed. But better safe to seal it than let it soak up water and rot.

Do not use 5 minute epoxy!!!

BTW, the difference between the epoxy sold in the hardware stores in applicator tubes and the epoxy bought in bulk for laminating fiberglass cloth is filler. The stuff in the tubes has fillers and coloring to make it thicker so it won't run, and the mix is made so equal parts will harden and the color is so you can tell when its mixed well. "Virgin" epoxy generally does not mix 1:1, it tends to be thin like maple syrup on a hot day and clear.

 

[proslambanomenos]

Re: RTV Silicone for Garboard Plug

Sand the hole clean, probe with a screwdriver to ensure no rot

Before I try doing this tonight, and this will sound dumb, and I am a n00b, but how do i know if there's rot, and if there is some, what can be done about it? Anything without refurbishing the whole transom?

-thanks

 

[legoman67]

Re: RTV Silicone for Garboard Plug

if there is rot the screw driver will sink in and the wood will seem mushy, and, god forbid, water will come out(thats how bad ours was) The only proper way to deal with it is to replace the entire thing. rot is like cancer. Once its started, its next to impossible to stop.